Prior to the forging press pressure contact phase during which the workpiece is engaged by the forging jaws of the pres rams, the rotary movement of the workpiece is arrested and stopped so that the ram jaws may radially act on the workpiece. Generally, such a known forging machine is endowed with a high and invariable number of stroke frequencies primarily used to forge long workpieces.
In such prior art forging machines, the workpiece is moved by manipulators both axially and rotatingly in peripheral direction. The rotary drive of the prior art manipulators is insured by a constantly running electric motor acting via a worm drive on a shaft rotating about an axis of rotation.
Corresponding to the required function, the rotary movement of the shaft about the axis of rotation is arrested during the pressure contact phase by the superimposition of a constant worm drive and a brake-spring system. With the known device, the driven worm is axially displaceable and supported axially via mechanical spring assemblies thus enabling the worm to axially move or be displaced in both directions. During the pressure contact phase, to exclude torque at the manipulator shaft axis due to the spring action, a disk brake is used to brake and correspondingly retain the constant rotary movement of the manipulator shaft axis of the worm wheel to the beginning of the pressure contact phase.
Due to the constant advance of the drive motor, the worm is screwed out against spring tension at the braked worm wheel. Upon termination of the pressure contact phase, the brake is disengaged so that the worm is reset again via the tensioned spring. An increased speed is formed over the contact speed at the worm wheel and at the manipulator tongs accordingly. The rotary angle lag resulting from the braking is recovered again.
In the course of the worm resetting movement and in functional relationship with the additionally accelerated masses, one does not only reach the center position due to resetting, but the system swings also into the opposite spring set and partly back again. Prior to the beginning of the new pressure contact time of the next working cycle, the brake is engaged again.
In case of the oscillatory system, spring tension, mass forces and speeds are in a direct physical relationship. A regular operation of the known mechanical brake-spring system may be only insured if the structurally determined parameters are maintained. Already with different ways of machining (roughing and refining), the relationship between contact time and idle time forms a variable resulting in different parameters for the oscillatory brake-spring system.
It is imperative for the oscillatory brake-spring system to be bound to a fixed stroke frequency of the forging machine. Since the rotary mass is different in response to the workpiece size, a mass change is accompanied by a disadvantageous effect on the known brake-spring system. In addition, friction and attenuation are changing in the current operation and wear is caused by the brake required in the rotary drive. Because the brake paths of a friction brake are not constant, the machine function is affected accordingly. Thus, with the known brakespring system the axial displacement of the worm shaft has control but is fixedly determined by the mechanical structure of the system itself. Such known system is not capable of being predeterminable controllable or adaptable to a variable forging sequence.